Generally, unlike a primary battery which may not be charged, a secondary battery is a battery which may be charged and discharged. The secondary battery may be used in small portable electronic devices such as a phone, a notebook computer, and a camcorder in the case of a low-capacity battery in which one battery cell is packaged in a pack form and may be configured in large capacity by connecting tens of battery cells in series or in parallel in the case of a power supply for driving a motor of devices requiring high power such as an electric vehicle.
The secondary battery may be manufactured in various types and as a representative type thereof, there may be a pouch type, a cylindrical type, and a prismatic type. In the case of the pouch type, the shape of the secondary battery is relatively free and is light in a weight and has been recently mainly used in slim and lightweight portable electronic devices.
Unlike the circular or prismatic secondary battery in which the case is molded in a thick metal material, in the case of the pouch type secondary battery, the case may be freely bent by attaching a thin metal film and an insulating film to both surfaces thereof and an inside thereof is provided with a space part in which an electrode group may be accommodated.
In a battery of a hybrid vehicle to which the pouch type secondary battery is applied, cells having a thin plate-like structure are made in one module and a package is configured by connecting a plurality of modules in series according to a specification of a hybrid vehicle.
By the package configured by connecting the plurality of modules in series, heat is generated from the cells at the time of charging and discharging and charging and discharging power of the battery is changed depending on temperature of the cells.
Therefore, the temperature of the cell needs to be kept in an appropriate range so that the battery is operated at internal temperature of the battery of, for example, 25 to 40°.
The battery cooling structure according to the related art has a battery case which includes an inner case in which a battery pack is compactly received, an installation part in which a control part controlling the battery of the battery pack is installed, an outer case housing the inner case, and a cooling fan installed in the outer case to cool the battery pack received the inner case.
The battery cooling structure according to the related art uses the cooling fan so as to cool the battery pack positioned inside the outer case using outer air, such that moisture included in the outer air may be introduced into the battery pack, thereby causing an electrical short due to the moisture introduced into the battery pack.
Further, there is a problem in that the battery pack may not be kept at a constant temperature using the outer air.
Further, there is a problem in that harmful gas such as ignition of the cell in the battery pack may be leaked to an outside of the outer case in time of emergency.
A background art of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2011-0003912 (Jan. 13, 2011).